Unmanned Aerial Vehicle Charging Station Management

ABSTRACT

Methods, devices, and systems of various embodiments are disclosed for managing an unmanned aerial vehicle (UAV). In various embodiments, the UAV may charge an onboard battery while docked at a docking terminal of a charging station. The UAV may receive a message from the charging station with an instruction to undock from the docking terminal. The UAV may undock from the docking terminal before charging of the onboard battery is complete in response to receiving the message from the charging station with the instruction to undock.

RELATED APPLICATIONS

This application is a divisional of U.S. Non-provisional patentapplication Ser. No. 15/166,989 entitled “Unmanned Aerial VehicleCharging Station Management” filed May 27, 2016, the entire contents ofwhich are hereby incorporated by reference for all purposes.

BACKGROUND

The range of an unmanned aerial vehicle (UAV) may be extended byrecharging onboard power cells (i.e., batteries) at one or more chargingstations in route to a destination. However, as the number of commercialand recreational UAVs increases, the demand for time on chargingstations may increase. Thus, a UAV needing to use a charging station mayhave to wait when all charging stations are occupied by other UAVs.Similarly, multiple UAVs may not be able to land at the same chargingstation at the same time. Efficient charging station resource managementmay enable UAVs that need recharging the most to receive a neededrecharge for completing a mission without having to cut the missionshort or returning to a base location. Such charging stations may beconfigured to autonomously make determination regarding a charging orderfor UAVs needing to dock at the charging station.

SUMMARY

Various embodiments include a charging station having a processor, andmethods for operating the charging station when receiving dockingrequests from two or more UAVs. Various embodiments may includedetermining a priority of a first UAV and a second UAV for using adocking terminal of the charging station based on an available powerlevel of each of the first and second UAVs. The first UAV may beinstructed to undock from the docking terminal in response todetermining that the second UAV has a higher priority.

Some embodiments may include establishing a communication link betweenthe UAV charging station and the second UAV, and receiving the availablepower level and a UAV ranking from the second UAV. In such embodiments,determining the priority of the first and second UAVs for using thedocking terminal may include determining the priority of the first andsecond UAVs for using the docking terminal by weighing the availablepower level and the UAV ranking of each of the first and second UAVs. Insome embodiments, the available power level may be weighted more heavilythan the UAV ranking when determining the priorities of the first andsecond UAVs for using the docking terminal in response to the availablepower level of either the first or second UAVs being below apredetermined low threshold. In some embodiments, the UAV ranking may begiven no weighting when determining the priorities of the first andsecond UAVs for using the docking terminal in response to the availablepower level of either the first or second UAVs being below apredetermined critical threshold. In some embodiments, the availablepower level may be given no weighting when determining the priorities ofthe first and second UAVs for using the docking terminal in response tothe UAV ranking of either the first or second UAVs being above apredetermined ranking.

In some embodiments, the docking request may include informationselected from a group consisting of UAV identification, UAVauthentication information, UAV ranking, available power level, and howlong the second UAV has been waiting to dock at the charging station. Insome embodiments, instructing the first UAV to undock from the dockingterminal may include information about another charging station. In someembodiments, instructing the first UAV to undock from the dockingterminal may include authorizing the first UAV to remain on the UAVcharging station but not in the docking terminal. In some embodiments,instructing the first UAV to undock from the docking terminal mayinclude instructing the first UAV to change to a different dockingterminal at the UAV charging station. In some embodiments, instructingthe first UAV to undock from the docking terminal may includeinstructing the first UAV to remain on the UAV charging station for abattery swap.

Further embodiments may include a UAV charging station including atransceiver, and a processor coupled to the docking terminal and thetransceiver and configured to perform operations of the methodssummarized above. Further embodiments may include a UAV charging stationhaving means for performing functions of the methods summarize above.Further embodiments may include a non-transitory processor-readablestorage medium having stored thereon processor-executable instructionsconfigured to cause a processor of a UAV charging station to performoperations of the methods summarize above.

Further embodiments include methods of managing UAV charging may includecharging an onboard battery of the UAV while docked at a dockingterminal of a charging station, receiving a message from the chargingstation with an instruction to undock from the docking terminal, andundocking from the docking terminal before charging of the onboardbattery is complete in response to receiving the message from thecharging station with the instruction to undock. Some embodiments mayfurther include determining, in response to receiving the message fromthe charging station with the instruction to undock, whether anavailable power level of the onboard battery is sufficient to reachanother charging station, and landing the UAV at a location removed fromthe docking terminal to wait for the docking terminal to becomeavailable to the UAV for charging in response to determining that theavailable power level of the onboard battery is insufficient to reachanother charging station. In some embodiments, landing the UAV at alocation removed from the docking terminal may include landing the UAVon the charging station in a waiting zone separate from the dockingterminal. In some embodiments, the received message from the chargingstation with the instruction to undock includes authorization to remainat the UAV charging station but not in the docking terminal.

Further embodiments may include a UAV including a transceiver and aprocessor configured to perform operations of the methods summarizedabove.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary embodiments, andtogether with the general description given above and the detaileddescription given below, serve to explain the features of the variousembodiments.

FIG. 1 is a schematic diagram of a UAV docked at a charging stationaccording to various embodiments.

FIG. 2 is a process flow diagram illustrating a method of managing a UAVcharging station according to various embodiments.

FIG. 3 is a process flow diagram illustrating a method of managing UAVcharging according to various embodiments.

FIG. 4 is a perspective view of a UAV and a schematic relief diagram ofa control unit and remote communication device according to variousembodiments.

FIG. 5 is a component diagram of an example server suitable for use withthe various embodiments.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theclaims.

Various embodiments include a charging station for UAVs. The chargingstation may include a communication system and processor configured todetermine a charging order or priority of a plurality of UAVs needing touse a docking terminal at the charging station. The charging order orpriority may be based on a measure of available onboard power and a UAVrank of each UAV. A UAV with a low priority that is docked at a dockingterminal of a charging station may be ordered to undock from the dockingterminal. The UAV charging station may be configured to determinewhether a currently charging UAV should undock from the docking terminalbased on a weighted priority of the UAV in which the currently chargingUAV's available power level (charge state) and priority are comparedagainst another UAV's available power level (charge state) and priorityof one or more UAV's.

The terms “unmanned aerial vehicle” and “UAV” are is used herein torefer to one of various types of aerial vehicles that may not utilizeonboard, human pilots. A UAV may include an onboard computing deviceconfigured to operate the UAV without remote operating instructions(i.e., autonomously), such as from a human operator or remote computingdevice. Alternatively, the onboard computing device may be configured tooperate the UAV with remote operating instruction or updates toinstructions stored in a memory of the onboard computing device. The UAVmay be propelled for movement in any of a number of known ways. Forexample, a plurality of propulsion units, each including one or morepropellers or jets, may provide propulsion or lifting forces for the UAVand any payload carried by the UAV for travel or movement. In additionor alternatively, the UAV may include wheels, tank-tread, floatationdevices or other non-aerial movement mechanisms to enable movement onthe ground or across water. The UAV may be powered by one or more typesof power source, such as electrical, chemical, electro-chemical, orother power reserve, which may power the propulsion units, the onboardcomputing device and/or other onboard components.

As used herein, the term “charging station” or “UAV charging station”refers to a location that includes at least one docking terminal with acharger for charging a UAV (e.g., battery thereof). As used herein, theterm “docking terminal” refers to a position at the charging station atwhich the UAV may dock and be charged by the charger. The dockingterminal may include (but is not limited to) elements for mechanicallycoupling, holding, and/or supporting a UAV docked at the dockingterminal. In some embodiments, the term “charger” refers to a device forcharging an onboard battery of a UAV while the onboard battery remainsonboard the UAV (i.e., without removing the battery for charging). Thecharger at the docking terminal may include (but is not limited to) anelectrical receptacle, cord, wireless charger, or mating device fortransferring electric charge to a UAV.

As used herein, the terms “dock,” “docked,” or “docking” refer to theact of connecting to and/or parking at a docking terminal of a chargingstation for more than a brief period. While docked at a dockingterminal, a UAV may be charging or may have stopped charging but remainsat the docking terminal (i.e., finished charging or ready to leave).While docked, UAVs may mechanically couple to the charger (e.g., adirect connection is formed) or the UAVs may land on or hang from asupport structure without a secure connection to the charger (e.g., forwireless charging).

The term “computing device” is used herein to refer to an electronicdevice equipped with at least a processor. Examples of computing devicesmay include a UAV recharging control, travel control, and/or missionmanagement computers, mobile devices (e.g., cellular telephones,wearable devices, smart-phones, web-pads, tablet computers, Internetenabled cellular telephones, Wi-Fi® enabled electronic devices, personaldata assistants (PDA's), laptop computers, etc.), personal computers,and server computing devices. In various embodiments, computing devicesmay be configured with memory and/or storage as well as networkingcapabilities, such as network transceiver(s) and antenna(s) configuredto establish a wide area network (WAN) connection (e.g., a cellularnetwork connection, etc.) and/or a local area network (LAN) connection(e.g., a wired/wireless connection to the Internet via a Wi-Fi® router,etc.).

The term “server” as used herein refers to any computing device capableof functioning as a server, such as a master exchange server, webserver, and a personal or mobile computing device configured withsoftware to execute server functions (e.g., a “light server”). Thus,various computing devices may function as a server, such as any one orall of cellular telephones, smart-phones, web-pads, tablet computers,Internet enabled cellular telephones, WAN enabled electronic devices,laptop computers, personal computers, and similar electronic devicesequipped with at least a processor, memory, and configured tocommunicate with a UAV. A server may be a dedicated computing device ora computing device including a server module (e.g., running anapplication that may cause the computing device to operate as a server).A server module (or server application) may be a full function servermodule, or a light or secondary server module (e.g., light or secondaryserver application). A light server or secondary server may be aslimmed-down version of server type functionality that can beimplemented on a personal or mobile computing device, such as a smartphone, thereby enabling it to function as an Internet server (e.g., anenterprise e-mail server) to a limited extent, such as necessary toprovide the functionality described herein. An example of serversuitable for use with the various embodiments is described withreference to FIG. 5.

Various embodiments may be implemented using a variety of chargingstations and/or charging station configurations. A charging station mayhave more than one docking terminal with one or more chargers forcharging one or more UAVs. In some embodiments, the docking terminal(s)may have a bracket or seating or otherwise be configured to receive andhold a UAV in-place while charging. The docking terminal and/or thecharger may be configured with coupling elements configured to mate withelements of the UAV for transferring electrical power, such as to anonboard battery of the UAV.

Various embodiments may be implemented using a variety of UAVconfigurations. A propulsion source for a UAV may be one or morepropellers that generate a lifting or propelling force sufficient tolift and/or move the UAV (including the UAV structure, motors,electronics, and power source) and any loads that may be attached to theUAV (e.g., a payload). The propulsion source may be powered by anelectrical power source, such as a battery. While the present disclosureis directed to examples of electric motor controlled UAVs, the claimsand embodiments may be applied equally to UAVs powered by variousadditional types of power source that may be resupplied with a productthat may be used or consumable to create energy.

Propulsion sources may be vertical or horizontally mounted depending onthe movement mode of the UAV. A common UAV configuration suitable foruse in the various embodiments is a “quad copter” configuration. In anexample quad copter configuration, four horizontally-configured rotarylift propellers and motors fixed to a frame. However, UAV's may have anynumber of rotary lift propellers and motors are fixed to the frame. Theframe may include a frame structure with landing skids that supports thepropulsion motors, power source (e.g., battery), payload securingmechanism, and so on. A payload may be attached in a central areaunderneath the frame structure platform of the UAV, such as an areaenclosed by the frame structure and skids underneath the power sourcesor propulsion units. A quad copter-style horizontal rotor UAV may travelin any unobstructed horizontal and vertical direction or may hover inone place. A quad copter UAV configuration is used for illustrativepurposes in the examples described herein; however, other UAV designsmay be used.

A UAV may be configured with processing components that enable the UAVto navigate, such as by controlling the motors to achievedirectionality, and communication components that enable the UAV toreceive position information and information from external systemsincluding servers, access points, other UAVs, and so on. The positioninformation may be associated with the current UAV position, waypoints,travel paths, avoidance paths/sites, altitudes, destination sites,locations of charging stations, relative locations of other UAVs,potential charging station sites, and/or the like. The positioninformation may be based on a relative position or an absolute position(i.e., geographic coordinates) obtained from a sensor (onboard orremote) or from communications with a computing device (e.g., server,global navigation satellite system (GNSS), or positioning beacon).

The UAV may periodically or continuously monitor onboard available powerlevels and determine whether the UAV has enough power to reach itsdestination in accordance with mission power parameters. The missionpower parameters may include power requirements for reaching thedestination of a course of the UAV. Also, the mission power parametersmay include or take into account a threshold level of reserve powerallowing a margin of error (e.g., determined from a statistical erroranalysis). In addition, the mission power parameters may includeinformation about payload encumbrances, route parameters, conditionsthat impact power consumption (e.g., inclement weather), deadlines(i.e., timing considerations), priority levels, and other informationabout one or more missions assigned to the UAV.

In case of an emergency or when available onboard power is insufficientto meet one or more mission power parameters, the UAV may assessavailable information to determine whether the UAV can dock at a dockingterminal in a charging station to recharge onboard batteries. Forexample, when head winds are heavier than expected, the UAV will expendmore power than expected to reach its destination, and therefore mayneed to recharge in order to reach the original destination.

Various embodiments include a charging station 110 including one or moredocking terminals 120 with chargers configured to recharge a UAV, suchas UAVs 400, 401, 402. Examples of chargers include electricalreceptacles, cords, wireless chargers, or mating devices fortransferring electric charge to a UAV. The charging station 110 may havemore than one docking terminal 120 and each docking terminal 120 mayhave more than one different type of charger. For example, one chargermay be configured to charge special types of UAVs, couple to specialtypes of UAV mating devices, or charge UAVs at a different rate thanother chargers. The charging station 110 illustrated in FIG. 1 is in theform of flat open deck platform; however, other configurations ofcharging stations may be used.

Multiple UAVs 400, 401, 402 may attempt to dock at the docking terminal120 to recharge onboard batteries of the UAVs 400, 401, 402, but onlyone of the UAVs 400, 401, 402 at a time can dock at the docking terminal120. Alternatively, one of the UAVs 400, 401, 402 that was unable todock at the docking terminal 120 may be able to land in a waiting zone105. The waiting zone 105 may be helpful for UAVs too low on power towait by hovering near the charging station 110 until a docked UAV (e.g.,400) departs. In particular embodiments, the waiting zone 105 does notprovide any charging capabilities for recharging a waiting UAV. While inthe waiting zone, the waiting UAV may be in a reduced power staterelative to when in flight and/or when charging on the docking terminal.

In various embodiments, the charging station 110 includes a control unit150. The control unit 150 may include a processor 151, one or moretransceivers 152 (e.g., Peanut, Bluetooth, Bluetooth LE, ZigBee, Wi-Fi®,radio frequency (RF) radio, etc.), a platform antenna 115, and a powermodule 153. The processor 151 may include memory 154 and sufficientprocessing power to conduct various control and computing operations forthe charging station 110. The processor 151 may be coupled to andcontrol the docking terminal 120 for charging UAVs docked thereon, suchas by being equipped with charging control algorithm and a chargecontrol circuit. The processor 151 may be directly powered from a powersource supplying power for charging the UAVs or from the power module153. The processor 151 may also be coupled to one or more motor oractuation mechanisms for holding or releasing UAVs docked on the dockingterminal 120.

The charging station control unit 150 may control and be coupled tosensors (not shown) such as cameras for observing the area surroundingthe charging station 110 and monitoring the UAVs 400, 401, 402approaching for landing.

The processor 151 may communicate with UAVs 400, 401, 402 through theone or more transceivers 152. A bi-directional wireless link 422 may beestablished between the platform antenna 115 and each of the UAVs 400,401, 402, such device-to-device (D2D) communications may use Long TermEvolution (LTE) Direct, Wi-Fi direct, or the like. The UAVs 400, 401,402 may also use inter-UAV wireless links 420 for directly communicatingto one another. The inter-UAV wireless links 420 may also use D2Dcommunication protocols. The charging station 110 may also includenetwork access ports (or interfaces) coupled to the processor 151 forestablishing data connections with a network, such as the Internet 550and/or a local area network coupled to other systems computers and aserver 500.

Charging stations (e.g., 110) may be located on building rooftops, whichare isolated locations that may provide security. However, highaltitudes often experience severe wind conditions that may damage ordestroy a UAV. While the charging station 110 is illustrated as a flatopen deck, numerous other configurations may be suitable for chargingthe UAVs in accordance with various embodiments. In various embodiments,the charging station 110 may deploy a grappling component or stabilizerto secure the UAV 400 to the charging station 110.

Different types of locations may be suitable for a UAV charging station110, such as (but not limited to) commercial buildings, power orcommunication towers, and/or the like. UAV charging stations are notlimited to being located on building rooftops or even man-made objects.For example, natural locations like cliffs, hilltops, rocks, openfields, or on a flotation device on a lake, pond, or river, and/or thelike may be suitable as a UAV charging station 110.

FIG. 2 illustrates a method 200 for managing a UAV charging stationaccording to various embodiments. With reference to FIGS. 1-2,operations of the method 200 may be performed by a platform control unit(e.g., 150), a server (e.g., server 500), or other computing devices.

In block 210, a processor (e.g., 151) of the charging station (e.g.,110) may receive a docking request. The processor may receive thedocking request via the one or more transceivers (e.g., 152) and theplatform antenna (e.g., 115). Receipt of the docking request may occur,for example, in response to performing device discovery to detect UAVsin proximity of the charging station. The docking request may includeadditional information, such as identification and authenticationinformation as well as details regarding an available power level of therequesting UAV and/or rank of the requesting UAV. Alternatively, suchadditional information may be requested and/or received separately. Theprocessor may be configured to receive more than one docking requestsimultaneously, but may handle each request individually in a similarfashion. The handling of each request may be performed simultaneously,but for ease of explanation the description of how only a single requestis handled is described herein.

In determination block 215, the processor may determine whether the UAVtransmitting the docking request has been properly authenticated andidentified. Authentication and identification information may berequested separately as part of determination block 215. In response todetermining that the requesting UAV is not properly authenticated oridentified (i.e., determination block 215=“No”), the processor maytransmit a rejection of the request in block 220, using the one or moretransceivers and the platform antenna, and await a further dockingrequest in block 210.

In response to determining that the requesting UAV is properlyauthenticated and identified (i.e., determination block 215=“Yes”), theprocessor may determine whether a docking terminal at the chargingstation is currently available (i.e., not occupied) in determinationblock 225.

In response to determining no docking terminal is currently available(i.e., determination block 225=“No”), the processor may determinewhether an occupying UAV (i.e., a UAV occupying the docking terminal) ischarging or idle (i.e., not charging) in determination block 240.

In response to determining that a docking terminal is currentlyavailable (i.e., determination block 225=“Yes”), in determination block230, the processor may determine whether multiple docking requests havebeen authenticated in determination block 215 and are still pending.

In response to determining that no other docking requests are pending(i.e., determination block 230=“No”), the processor may transmit amessage to the requesting UAV indicating a docking terminal at thecharging station is available (i.e., Go-for-docking”) in block 236.Prior to transmitting the Go-for-docking message, the processor may openany hatches or release mechanisms prior to a UAV initiating dockprotocols with the docking terminal. Based on the Go-for-dockingmessage, the requesting UAV may be allowed to dock at the dockingterminal

In response to determining that multiple docking requests are pending(i.e., determination block 230=“Yes”), the processor may determine anavailable power level for each of the multiple UAVs with pending dockingrequests in block 232. Additionally or alternatively in block 232, theprocessor may determine a rank associated with each of the multiple UAVswith pending docking requests. If the processor does not already havethis information (i.e., processor was not provided with the initialdocking request), the processor may transmit a request to theappropriate UAVs as needed (and/or servers associated with the UAVs).

In block 234, the processor may determine the UAV that has the highestpriority based on the determined available power levels and thedetermined ranks. In determining the UAV with the highest priority, theprocessor may determine priorities of the multiple UAVs with pendingdocking requests. The priority determination in block 234 may be aweighted priority, with available power level having more influence thanrank, with rank having more influence than available power level, orwith both power level and rank having equal weighting. In addition,other factors such as how long a UAV has been waiting may influence thatUAVs rank. Alternatively, the priority determination in block 234 may bebased on one or more thresholds. For example, if an available powerlevel is below a predetermined low threshold, the available power may beweighted more heavily than the UAV ranking. Also, if an available powerlevel is below a predetermined critical threshold, the ranking may begiven no weighting when determining the charging order or priority forthe charging station. As a further alternative, if either UAV has aranking above a certain predetermined ranking, the available power levelmay be given no weighting when determining the charging order orpriority. According to various embodiments, UAV ranks may be determinedin any suitable manner and/or be based on any suitable criteria (e.g.,based on a higher landing fee or subscription fee, higher valuedpayload, etc.).

When multiple UAVs are being assessed, the processor may transmit (e.g.,using the one or more transceivers and the platform antenna) at leasttwo different types of messages in response to the prioritydetermination in block 234, namely a Go-for-docking message in block 236to the UAV with the highest priority and one or more request rejectionsin block 280 to any other UAVs.

Returning to determination block 240, in response to determining thatthe occupying UAV is charging (i.e., determination block 240=“Yes”), theprocessor may determine an available power level and/or a rankassociated with the charging UAV and each other UAV with a pendingdocking request in block 250.

In block 260, the processor may determine UAV priorities, which mayinclude determining the priorities of multiple UAVs and/or the UAV thathas the highest priority. The determined UAV priorities may be based onthe determined available power levels, the determined ranks, and/or acombination thereof. In determination block 270, the processor maydetermine whether the docking terminal occupant matches the UAV with thehighest priority based on the determination of the UAV that has thehighest priority.

In response to determining that the docking terminal occupant has thehighest priority (i.e., determination block 270=“Yes”), the processormay, in block 280, transmit request rejection messages to any other UAVsthat had made a docking request.

In response to determining that the docking terminal occupant does nothave the highest priority (i.e., determination block 270=“No”) or inresponse to determining that the occupying UAV is not charging (i.e.,determination block 240=“No”), the processor may transmit (e.g., usingthe one or more transceivers and the platform antenna) a “move” messageto the occupying UAV in block 242.

The move message in block 242 may require the occupying UAV to leave(i.e., vacate) the docking terminal. The move message may includeinstructions to undock accompanied by information about another dockingterminal (e.g., at the current charging station or at another chargingstation remote from the charging station 110) that may be available asan alternate. The fact that another docking terminal (or other chargingstation) is available may be considered when making the prioritydetermination in blocks 234, 260. Alternatively, the move message mayalso indicate that the vacating UAV may remain at the charging stationbut not at the docking terminal connected to the charger (e.g., move tothe waiting zone 105). Alternative services may be offered in thewaiting zone, such as a battery swap. In this way, although a UAV has tomove to the waiting zone, the waiting UAV may receive a fully chargedbattery or other needed components.

Although the move message may instruct the vacating UAV to move toanother docking terminal that is technically suitable for the vacatingUAV, the other docking terminal may not be as desirable or optimal forthe vacating UAV. For example, the other docking terminal may not haveoptimal connections or may charge more slowly than the docking terminalbeing vacated. Alternatively, the other docking terminal may not besuitable for charging the vacating UAV (e.g., the connection(s) orcharger may not be compatible with the vacating UAV) but may be used asa waiting zone (e.g., 105) by the vacating UAV. Thus, included withinthe move message or as part of a separate message, the charging stationmay transmit information about the other docking terminal (e.g.,specifications, connection types, charging rate, available chargingtime, etc.) to the vacating UAV for a control unit or operator of thevacation UAV to determine whether docking at the other docking terminalis appropriate.

In determination block 245, the processor may determine whether thedocking terminal of the charging station is clear (i.e., the occupyingUAV has undocked from the docking terminal). This determination enablesthe processor to detect when, for some reason, the occupying UAV has notmoved, such as when the occupying UAV did not receive the message tomove or the occupying UAV may be unable to move.

In response to determining that the occupying UAV has not yet moved(determination block 245=“No”), the processor may once again transmit a“move” message to the occupying UAV in block 242. Alternatively, theprocessor may provide an indicator to a person or other device (e.g., atowing UAV or vehicle) at the charging station to manually move theoccupying UAV.

In response to determining that the occupying UAV has moved(determination block 245=“Yes”), the processor in determination block230 may determine whether multiple docking requests have beenauthenticated and are still pending, as described above. With thepreviously occupying UAV no longer in the docking terminal, if a singleUAV has requested docking the processor may transmit a Go-for-docking inblock 236. Otherwise, the processor may eventually transmit one of twodifferent types of messages, namely a Go-for-docking message in block236 to the UAV with the highest priority and one or more requestrejections in block 280 to any other UAVs.

The processor may maintain a register of a current status of any UAVcurrently docked or parked at the charging station and/or at aparticular docking terminal if the charging station includes more thanone docking terminal and/or a waiting zone. For example, this registermay indicate when a docking terminal is occupied by a UAV charging or bya UAV that is idle and not charging.

FIG. 3 illustrates a method 300 of managing UAV charging according tovarious embodiments. With reference to FIGS. 1-3, operations of themethod 300 may be performed by one or more processors (e.g., 460 in FIG.4) and/or a control unit (e.g., 450 in FIG. 4) of a UAV (e.g., 400, 401,402). For ease of explanation, various operations of the method 300 aredescribed as being performed by the processor, although one or moreadditional components may also be used.

In block 310, the processor may dock the UAV at the docking terminal(e.g., 120) of a charging station (e.g., 110) for charging. The dockingof the UAV at the docking terminal may include connecting to a charger.The connection to a charger may include coupling with mechanicalcontacts or positioning the UAV for wireless charging.

In block 320, an onboard battery (e.g., 470 in FIG. 4) of the UAV may becharged by the charger, while docked at the docking terminal of thecharging station. In addition to the UAV charging the onboard battery bythe charger of the docking terminal, the UAV may also deploy or make useof onboard solar panels or other energy harvesting components (e.g.,wind harvesting) in order to supplement the charging of the onboardbattery.

In determination block 325, the processor may determine whether amessage is received with an instruction to undock from the dockingterminal. In response to determining that no message is received with aninstruction to undock (i.e., determination block 325=“No”), theprocessor may determine whether charging is complete in determinationblock 335. The processor may determine charging is complete in responseto the battery being charged to a designated level. Such a designatedlevel may correspond to a level of charge needed to reach a particulardestination, a preset percentage (e.g., 90% charged) or amount ofcharge, a level of charge associated with a predetermined flight-time ofthe UAV, etc. The designated level of charge may take into account acharging limit designed to extend a long-term life of the battery. Thus,the designated level may be a fully charged state or less than a fullycharged state (i.e., less than or equal to 100% charged).

In response to determining that a message is received with aninstruction to undock (i.e., determination block 325=“Yes”), theprocessor may determine whether the UAV is able to undock from thedocking terminal in determination block 330. The UAV may be unable toundock due to a mechanical or other problem and/or an onboard battery isnot sufficiently charged for the UAV to undock. The processor may takeinto account the available power level of the onboard battery to ensurethat the UAV can undock and return to the docking terminal when thedocking terminal becomes available. When deciding whether the UAV isable to undock, the processor may assess where and for how long the UAVmay have to remain while waiting to return to the docking terminal.Thus, even though the UAV may be capable of undocking from the dockingterminal (i.e., no mechanical or other problem and sufficient power toundock), the processor may determine that the UAV is unable to dock ifthe UAV would not be able to return to the occupied docking terminal orreach another docking terminal.

The determinations regarding whether a message is received with aninstruction to undock in determination block 325 and the determinationwhether charging is complete in determination block 335 may be a passivedetermination. Thus, if no instruction to undock is received andcharging is not complete, the UAV continues to charge the onboardbattery in block 320 until either the message from the charging stationwith the instruction to undock is received or charging is complete.

In response to determining that charging is not complete (i.e.,determination block 335=“No”), the UAV may continue charging the onboardbattery in block 320. In response to determining that charging iscomplete (i.e., determination block 335=“Yes”), the processor maydetermine whether the UAV is able to undock from the docking terminal indetermination block 330. For example, although the onboard battery ofthe UAV is fully charged (or sufficiently charged to reach its nextdestination or charging station), the UAV may be blocked from undockingor unable to undock due to a mechanical or other problem.

In response to determining that the UAV is not able to undock (i.e.,determination block 330=“No”), the UAV may stay docked at the dockingterminal in block 340 and optionally either continue charging theonboard battery in block 320 if charging of the onboard battery is notcomplete, or once again determine whether the UAV is able to undock fromthe docking terminal in determination block 330 if/when charging of theonboard battery is complete. Thus, if the UAV is unable to undock, butis fully (or sufficiently) charged, the processor may keep the UAVdocked at the docking terminal until the UAV is able to undock. If theUAV remains at the docking terminal long enough and depletes sufficientpower, the UAV may once again charge the onboard battery in block 320.Additionally, the UAV may inform the charging station as to why the UAVdid not undock and/or provide an acknowledgement to the charging stationthat the message with the instructions to undock were received.

In response to determining that the UAV is able to undock (i.e.,determination block 330=“Yes”), the processor may determine whether anavailable power level of the onboard battery is sufficient to reach adestination of the UAV (e.g., a mission destination, home base, anintermediate charging station, etc.) in determination block 345.Although the onboard batteries of the UAV may not be full, the onboardbatteries may hold an available power level sufficient to reach thedestination. Alternatively, even if the onboard batteries of the UAV arefull and/or charging is complete (e.g., determination block 335=“Yes”),the available power level may not be sufficient to reach a finaldestination, in which case an intermediate or other destination (e.g.,an intermediate charging station) may be considered the destination fordetermining whether the available power level of the onboard battery issufficient in determination block 345.

In response to determining that the available power level of the onboardbattery is sufficient to reach the destination of the UAV (i.e.,determination block 345=“Yes”), the processor may direct the UAV toundock and head to the destination in block 350.

In response to determining that the available power level of the onboardbattery is not sufficient to reach the destination of the UAV (i.e.,determination block 345=“No”), the processor may determine whether theavailable power level of the onboard battery is sufficient to reachanother docking terminal in determination block 355.

In response to determining that the available power level of the onboardbattery is sufficient to reach another docking terminal (i.e.,determination block 355=“Yes”), the processor may direct the UAV toundock and head to the other docking terminal in block 360.

In response to determining that the available power level of the onboardbattery is not sufficient to reach another docking terminal (i.e.,determination block 355=“No”), the processor may direct the UAV to landat a safe landing site in block 365. Such a safe landing site may be thewaiting zone (e.g., 105) at the same charging station as the dockingterminal being vacated, a waiting zone at another charging station, aformal waiting zone (i.e., designated for UAV waiting) remote from anycharging station, or an informal waiting zone (i.e., a remote locationat which the UAV may safely land and wait like at a waiting zone).

The UAV may be provided ahead of time with charging location dataregarding possible charging stations and/or docking terminals.Information about one or more charging stations, including one or moredocking terminals at a charging station is herein referred to as“charging location data.” In addition, the UAV may be provided withwaiting zone information regarding charging stations with waiting zonesor locations to safely land to use like a waiting zone (i.e., formal orinformal waiting zones). Information about waiting zones at chargingstations and safe landing sites remote from charging stations is hereinreferred to as “waiting zone information.” A server (e.g., 500) maycompile such charging location data and/or waiting zone information fromprior visits by the UAV 400, information received from other UAVs,information collected by sensors located at charging stations or safelanding sites (e.g., sensors deployed by the UAV or placed there byother means), or information otherwise obtained and maintained by theserver 500. Alternatively, the UAV may autonomously identify one or morecharging stations, docking terminals, and/or safe landing sites, such asthe first available docking terminal or safe landing site that is notfar from the original course to a destination. Thus, the UAV may performa real-time site survey in order to assess a site and determine whetherthat site is suitable for charging and/or waiting. In variousembodiments, the UAV may transmit information determined from thereal-time site survey and/or otherwise received/collected to the serverfor updating. The information transmitted to the server may becomeinaccurate (i.e., decay) over time and thus may be associated by the UAVand/or the server with a time, such as when the information was receivedand/or collected.

In block 370, the processor may wait for the docking terminal (i.e.,either the previously vacated docking terminal or another dockingterminal) to become available. The wait may be a designated period afterwhich the processor transmits a request to dock at the previouslyvacated docking terminal and/or another docking terminal for charging.During the designated period, the processor may power-down to the extentpossible. Alternatively, the processor may passively wait for a messagefrom the charging station (i.e., monitor for receipt of a message fromthe charging station without actively transmitting a message or requestto dock). While waiting, the processor may power-down and/or conservepower as much as possible.

In determination block 375, the processor may determine whether thedocking terminal has become available. In response to determining thatthe docking terminal is not available (i.e., determination block375=“No”), the processor may continue to wait for the docking terminalto become available in block 370.

In response to determining that the docking terminal is available (i.e.,determination block 335=“Yes”), the UAV may redock with the dockingterminal in block 380 and resume charging the onboard battery in block320.

Before reaching a destination, the UAV 400 may change course based onupdated information received regarding mission power parameters orcharging station data. The UAV 400 may access an update to the missionpower parameters or a charging station availability update at any pointalong any course or while at a site. For example, based on a sensorreading at a particular charging station, the UAV 400 may determinecurrent charging rates are lower than expected. In response to thisdetermination, the UAV 400 may reassess the suitability of the currentcharging station. Alternatively, one or more of the other UAVs 401, 402may have reported better than normal charging relating to an alternativecharging station. As a further alternative, the server 500 may provideinformation indicating either mission power parameters or chargingstation conditions have changed such that the UAV 400 may need toreassess the suitability of the charging station and may change coursetoward another charging station.

Mission power parameters may include details regarding powerrequirements of one or more missions. The power requirements may furtherinclude route parameters, reserve power thresholds, payloadencumbrances, temporal parameters, and mission priorities. The UAV 400may compare such power requirements to current onboard power levels inorder to determine whether the UAV 400 has sufficient onboard power tosafely complete all missions or select missions. Temporal parameters mayinclude mission timing, deadlines, time-of-day, date, or otherinformation associated with time. In addition, since mission powerparameters may change, the UAV 400 may be provided with updates tomission power parameters from time to time.

In various embodiments, the mission power parameters may includeprojected energy expenditures associates with a particular course to adestination. Such projected energy expenditures may be determined basedon distance or travel times, and recalculated in real-time. In addition,route parameters may include other factors associated with a course,such as higher or lower than normal power consumption rates. Missionpower parameters may identify a minimum power level (or reserve powerlevel) that must be maintained at each stage in a mission in order toprovide safe margins for handling unexpected problems, such as weatherissues, payload issues, or hardware issues that could require anemergency divert or consume more power than expected. If power reserveson the UAV fall below such minimums, parking without charging at asuitable site may be required if recharging at a charging station is notan option, or other alternative power replacement methods are available(e.g., battery swap, or even refueling for UAVs with a combustionengine).

In various embodiments, reserve power thresholds may be a valueassociated with a predetermined percentage or quantity of onboard powerrecommended be kept in reserve for a mission at various phases in thetravel path (e.g., midway, at the destination, before starting to park,etc.). Alternatively, the value of the reserve power thresholds may bemeasured in terms of motor hours (i.e., a period of time in which one ormore motors expend onboard power), a distance/range that the UAV mayachieve using onboard power stores, or flight-time remaining. Higherreserve power thresholds may be used for missions with more uncertaintyregarding needed power. For example, risk factors from route parametersmay increase the value of the reserve power threshold specified for amission. A total mission power requirement may include an amount ofpower reflected by the reserve power threshold, in addition to projectedpower expenditures for the mission.

FIG. 4 illustrates a UAV, such as the UAV 400 (or 401, 402) of FIG. 1,in accordance with various embodiments. With reference to FIGS. 1-4, theUAV 400 may include a number of rotors 410, rotor arms 411, and a frame415. The frame 415 may provide structural support for the motorsassociated with the rotors 410, landing gear, and a control unit 450.The frame 415 may be sufficiently strong to support the maximum loadweight for the combination of the components of the UAV 400 and, in somecases, a payload. For ease of description and illustration, somedetailed aspects of the UAV 400 are omitted such as wiring, framestructure, interconnects, or other features that would be known to oneof skill in the art. For example, while the UAV 400 is shown anddescribed as having a frame 415 having a number of support members orframe structures, the UAV 400 may be constructed using a molded frame inwhich support is obtained through the molded structure. In theillustrated embodiments, the UAV 400 has four rotors 410. However, moreor fewer than four rotors 410 may be used.

The UAV 400 may further include a control unit 450 (e.g., 150 in FIG. 1)that may house various circuits and devices used to power and controlthe operation of the UAV 400. The control unit 450 may include aprocessor 460 (e.g., 151 in FIG. 1), a power module 470, a charginginterface 472, payload-securing units 475, an input module 480, sensors482, an output module 485, and a radio module 490. The processor 460 mayinclude or be coupled to memory 461 and a navigation unit 463. Theprocessor 460 may be configured with processor-executable instructionsto control travel and other operations of the UAV 400, includingoperations of the various embodiments. The processor 460 may be coupledto one or more payload-securing units 475 and sensors 482. Thepayload-securing units 475 may include an actuator motor that drives agripping and release mechanism and related controls that are responsiveto the control unit 450 to grip and release a payload in response tocommands from the control unit 450.

The sensors 482 may be optical sensors, radio sensors, a camera, orother sensors. Alternatively or additionally, the sensors 482 may becontact or pressure sensors that may provide a signal that indicateswhen the UAV 400 has made contact with a surface. The power module 470may include one or more batteries that may provide power to variouscomponents, including the processor 460, the payload-securing units 475,the input module 480, the sensors 482, the output module 485, and theradio module 490. In addition, the power module 470 may include energystorage components, such as rechargeable batteries. An external powersource, such as a charger from a charging station (e.g., 110 in FIG. 1)may supply power to the UAV 400 through the charging interface 472. Thecharging interface 472 may have mechanical contacts for receivingelectricity through conduction. Alternatively, or additionally, thecharging interface 472 may be configured to receive power throughwireless charging. The processor 460 may be configured withprocessor-executable instructions to control the charging of the powermodule 470 (i.e., the storage of harvested energy), such as by executinga charging control algorithm using a charge control circuit.Alternatively or additionally, the power module 470 may be configured tomanage its own charging. The processor 460 may be coupled to an outputmodule 485, which may output control signals for managing the motorsthat drive the rotors 410 and other components, such as a grapplingcomponent (not shown).

Through control of the individual motors of the rotors 410, the UAV 400may be controlled as the UAV 400 progresses toward a destination. Theprocessor 460 may receive data from the navigation unit 463 and use suchdata in order to determine the present position and orientation of theUAV 400, as well as the appropriate course towards the destination orintermediate sites. In various embodiments, the navigation unit 463 mayinclude a GNSS receiver system (e.g., one or more global positioningsystem (GPS) receivers) enabling the UAV 400 to navigate using GNSSsignals. Alternatively or in addition, the navigation unit 463 may beequipped with radio navigation receivers for receiving navigationbeacons or other signals from radio nodes, such as navigation beacons(e.g., very high frequency (VHF) omni-directional range (VOR) beacons),Wi-Fi® access points, cellular network sites, radio station, remotecomputing devices, other UAVs, etc.

The processor 460 and/or the navigation unit 463 may be configured tocommunicate with a server through a wireless connection (e.g., acellular data network) to receive data useful in navigation, providereal-time position reports, and assess data. An avionics module 467coupled to the processor 460 and/or the navigation unit 463 may beconfigured to provide travel control-related information such asaltitude, attitude, airspeed, heading and similar information that thenavigation unit 463 may use for navigation purposes, such as deadreckoning between GNSS position updates. The avionics module 467 mayinclude or receive data from a gyro/accelerometer unit 465 that providesdata regarding the orientation and accelerations of the UAV 400 that maybe used in navigation and positioning calculations.

The processor 460 may use the radio module 490 to conduct wirelesscommunications with a variety of wireless communication devices, such asa beacon, server, smartphone, tablet, or other computing device withwhich the UAV 400 may be in communication. Wireless communications(e.g., using a bi-directional wireless link 422) may be establishedbetween a UAV antenna 491 of the radio module 490 and platform antenna115 of the charging station 110. The radio module 490 may be configuredto support multiple connections with different wireless communicationdevices. The UAV 400 may communicate with a server through one or moreintermediate communication links, such as one or more network nodes orother communication devices.

In various embodiments, the radio module 490 may be configured to switchbetween a cellular connection and a Wi-Fi® or other form of radioconnection depending on the location and altitude of the UAV 400. Forexample, while in flight at an altitude designated for UAV traffic, theradio module 490 may communicate with a cellular infrastructure in orderto maintain communications with a server. An example of a flightaltitude for the UAV 400 may be at around 400 feet or less, such as maybe designated by a government authority (e.g., FAA) for UAV flighttraffic. At this altitude, it may be difficult to establishcommunication with some of the wireless communication devices usingshort-range radio communication links (e.g., Wi-Fi®). Therefore,communications with other wireless communication devices may beestablished using cellular telephone networks while the UAV 400 is atflight altitude. Communication between the radio module 490 and thecharging station 110 may transition to a short-range communication link(e.g., Wi-Fi® or Bluetooth®) when the UAV 400 moves closer to thecharging station 110. Similarly, the UAV 400 may include and employother forms of radio communication, such as mesh connections with otherUAVs or connections to other information sources (e.g., balloons orother stations for collecting and/or distributing weather or other dataharvesting information).

In various embodiments, the control unit 450 may be equipped with theinput module 480, which may be used for a variety of applications. Forexample, the input module 480 may receive images or data from an onboardcamera or sensor, or may receive electronic signals from othercomponents (e.g., a payload). The input module 480 may receive anactivation signal for causing actuators on the UAV to deploy clamps(e.g., grappling component) or similar components for securing itself.In addition, the output module 485 may be used to activate components(e.g., an energy cell, an actuator, an indicator, a circuit element, asensor, a grappling component, adjustment of landing columns, and/or anenergy-harvesting element).

While the various components of the control unit 450 are illustrated asseparate components, some or all of the components (e.g., the processor460, the output module 485, the radio module 490, and other units) maybe integrated together in a single device or module, such as asystem-on-chip module.

When selecting from multiple available charging stations and/or dockingterminals, the processor 460 of the UAV 400 may select a preferredcharging station and/or docking terminal based on various factors, suchas (but not limited to) which one best meets the current mission powerparameters of the UAV 400 based on its location. The UAV 400 may takemany considerations into account, such as (but not limited to) a speedat which the docking terminal charges, how long the docking terminal maybe available, safety, cost, and/or the like, before selecting aparticular charging station and/or a particular docking terminal at acharging station. The UAV 400 may communicate the preference for aparticular charging station and/or docking terminal when transmitting adocking request to a particular charging station (e.g., in block 210 inFIG. 2 in which the charging station receives a docking request).

The UAV 400 may access charging station data from an onboard source(e.g., memory 461, sensors 482, or input module 480) or a remote source(e.g., server 500 or another source on the Internet 550). In addition,charging station data may originate or come directly from other UAVs401, 402. For example, the server 500 may provide general informationabout the coordinates of the charging station 110 or other informationsuch as time-of-day, and weather related information. Further, whilecharging batteries at the charging station 110, the UAV 400 may receivea charging station data updates (i.e., changes of availability of one ormore other charging stations) or other information such as notice of anapproaching storm or other events.

Some charging station sites may have time-of-day restrictions, requirecertain authorizations, or have other access limitations. Risks at asite may reflect a likelihood that people or creatures might interfereor tamper with the UAV 400. For example, the charging station data mayreflect a preference for the rooftops of commercial buildings, whichtend to be safer than high-traffic areas. Risks assessments may alsoreflect how stable or reliable the positions at a site may be for a UAV400. For example, loose surfaces or fixtures that yield or collapseunder the weight of a UAV may increase the risk of a site.

In some embodiments, the information stored in the memory of the UAV 400may have a limited useful life, which may be indicated when theinformation is obtained (e.g., by an expiration time). The UAV 400 maytrack the expiration of the information stored in the memory using atimer or the like. For example, if the database information has expiredor is otherwise beyond the indicated useful life, the UAV processor maycontact the server to reload the latest database information. In someembodiments, a UAV storing expired database information may not beallowed to deviate from a current course, except in an emergency.

In some embodiments, the database information stored and/or maintainedon a given server (e.g., 500) may be populated by other servers (orentities) or by access to other servers (or entities). For instance, aserver may be configured to query or otherwise obtain event informationfrom an entity/server associated with a restricted area in which anevent may be taking place or may be scheduled to take place in therestricted area.

Various forms of computing devices may be used to communicate with aprocessor of a UAV, including personal computers, mobile computingdevices (e.g., smartphones, etc.), servers, laptop computers, etc., toimplement the various embodiments including the embodiments describedwith reference to FIGS. 1-5. Such computing devices may typicallyinclude, at least, the components illustrated in FIG. 5, whichillustrates an example server computing device, server 500. Withreference to FIGS. 1-5, the server 500 may typically include a processor501 coupled to volatile memory 502 and a large capacity nonvolatilememory, such as a disk drive 503. The server 500 may also include afloppy disc drive, compact disc (CD) or digital video disc (DVD) drive506 coupled to the processor 501. The server 500 may also includenetwork access ports 504 (or interfaces) coupled to the processor 501for establishing data connections with a network, such as the Internetand/or a local area network 505 coupled to other system computers andservers. Similarly, the server 500 may include additional access ports,such as USB, Firewire, Thunderbolt, and the like for coupling toperipherals, external memory, or other devices.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the operations of the various embodiments must beperformed in the order presented. As will be appreciated by one of skillin the art the order of operations in the foregoing embodiments may beperformed in any order. Words such as “thereafter,” “then,” “next,” etc.are not intended to limit the order of the operations; these words areused to guide the reader through the description of the methods.Further, any reference to claim elements in the singular, for example,using the articles “a,” “an” or “the” is not to be construed as limitingthe element to the singular.

The various illustrative logical blocks, modules, circuits, andalgorithm operations described in connection with the embodimentsdisclosed herein may be implemented as electronic hardware, computersoftware, or combinations of both. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and operations have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the claims.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the aspectsdisclosed herein may be implemented or performed with a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general-purpose processor maybe a microprocessor, but, in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of receiver smartobjects, e.g., a combination of a DSP and a microprocessor, a pluralityof microprocessors, one or more microprocessors in conjunction with aDSP core, or any other such configuration. Alternatively, someoperations or methods may be performed by circuitry that is specific toa given function.

In one or more exemplary aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable storagemedium or non-transitory processor-readable storage medium. Theoperations of a method or algorithm disclosed herein may be embodied ina processor-executable software module or processor-executableinstructions, which may reside on a non-transitory computer-readable orprocessor-readable storage medium. Non-transitory computer-readable orprocessor-readable storage media may be any storage media that may beaccessed by a computer or a processor. By way of example but notlimitation, such non-transitory computer-readable or processor-readablestorage media may include RAM, ROM, EEPROM, FLASH memory, CD-ROM orother optical disk storage, magnetic disk storage or other magneticstorage smart objects, or any other medium that may be used to storedesired program code in the form of instructions or data structures andthat may be accessed by a computer. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk, and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofnon-transitory computer-readable and processor-readable media.Additionally, the operations of a method or algorithm may reside as oneor any combination or set of codes and/or instructions on anon-transitory processor-readable storage medium and/orcomputer-readable storage medium, which may be incorporated into acomputer program product.

The preceding description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the claims. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof the claims. Thus, the present disclosure is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the following claims and the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of managing unmanned aerial vehicle(UAV) charging, comprising: charging an onboard battery of the UAV whiledocked at a docking terminal of a charging station; receiving a messagefrom the charging station with an instruction to undock from the dockingterminal; and undocking from the docking terminal before charging of theonboard battery is complete in response to receiving the message fromthe charging station with the instruction to undock.
 2. The method ofclaim 1, further comprising: determining, in response to receiving themessage from the charging station with the instruction to undock,whether an available power level of the onboard battery is sufficient toreach another charging station or another docking terminal at thecharging station; and landing the UAV at a location removed from thedocking terminal to wait for the docking terminal to become available tothe UAV for charging in response to determining that the available powerlevel of the onboard battery is insufficient to reach another chargingstation or another docking terminal at the charging station.
 3. Themethod of claim 2, wherein landing the UAV at the location removed fromthe docking terminal includes landing the UAV on the charging station ina waiting zone separate from the docking terminal.
 4. The method ofclaim 1, wherein the received message from the charging station with theinstruction to undock includes authorization to remain at the chargingstation but not in the docking terminal.
 5. The method of claim 4,further comprising: directing the UAV, in response to receiving themessage from the charging station with the instruction to undock, tomove to a location at the charging station that is not in the dockingterminal.
 6. The method of claim 2, further comprising: determiningwhether the docking terminal has become available; and redocking at thedocking terminal in response to determining that the docking terminalhas become available.
 7. The method of claim 1, further comprising:determining, in response to receiving the message from the chargingstation with the instruction to undock, whether an available power levelof the onboard battery is sufficient to reach a destination of the UAV;and directing the UAV to head to the destination after undocking fromthe charging station in response to determining that the available powerlevel of the onboard battery is sufficient to reach the destination ofthe UAV.
 8. The method of claim 7, further comprising: determining, inresponse to determining that the available power level of the onboardbattery is not sufficient to reach the destination of the UAV, whetheran available power level of the onboard battery is sufficient to reachanother charging station or another docking terminal at the chargingstation; directing the UAV to another charging station or anotherdocking terminal at the charging station in response to determining thatthe available power level of the onboard battery is sufficient to reachanother charging station or another docking terminal at the chargingstation; and landing the UAV at a location removed from the dockingterminal to wait for the docking terminal to become available to the UAVfor charging in response to determining that the available power levelof the onboard battery is insufficient to reach another charging stationor another docking terminal at the charging station.
 9. The method ofclaim 1, further comprising: determining, in response to receiving themessage from the charging station with the instruction to undock,whether the UAV is able to undock from the docking terminal at thecharging station; and staying docked at the docking terminal in responseto determining that the UAV is not able to undock from the dockingterminal.
 10. An unmanned aerial vehicle (UAV), comprising: atransceiver configured to communicate with charging stations; a batteryconfigured to power a component of the UAV; a charging interface forreceiving power for recharging the battery; and a processor coupled tothe transceiver, the charging interface, and the battery, wherein theprocessor is configured with processor-executable instructions to:charge the battery while docked at a docking terminal of a chargingstation; receive a message from the charging station with an instructionto undock from the docking terminal; and undock from the dockingterminal before charging of the battery is complete in response toreceiving the message from the charging station with the instruction toundock.
 11. The UAV of claim 10, wherein the processor is furtherconfigured to: determine, in response to receiving the message from thecharging station with the instruction to undock, whether an availablepower level of the battery is sufficient to reach another chargingstation or another docking terminal at the charging station; and landthe UAV at a location removed from the docking terminal to wait for thedocking terminal to become available to the UAV for charging in responseto determining that the available power level of the battery isinsufficient to reach another charging station or another dockingterminal at the charging station.
 12. The UAV of claim 11, wherein theprocessor is configured with processor-executable instructions such thatlanding the UAV at the location removed from the docking terminalincludes landing the UAV on the charging station in a waiting zoneseparated from the docking terminal.
 13. The UAV of claim 10, whereinthe processor is configured with processor-executable instructions suchthat the received message from the charging station with the instructionto undock includes authorization to remain at the charging station butnot in the docking terminal.
 14. The UAV of claim 13, wherein theprocessor is further configured to: direct the UAV, in response toreceiving the message from the charging station with the instruction toundock, to move to a location at the charging station that is not in thedocking terminal.
 15. The UAV of claim 11, wherein the processor isfurther configured to: determine whether the docking terminal has becomeavailable; and redock at the docking terminal in response to determiningthat the docking terminal has become available.
 16. The UAV of claim 10,wherein the processor is further configured to: determine, in responseto receiving the message from the charging station with the instructionto undock, whether an available power level of the battery is sufficientto reach a destination of the UAV; and direct the UAV to head to thedestination after undocking from the charging station in response todetermining that the available power level of the battery is sufficientto reach the destination of the UAV.
 17. The UAV of claim 16, whereinthe processor is further configured to: determine, in response todetermining that the available power level of the battery is notsufficient to reach the destination of the UAV, whether an availablepower level of the battery is sufficient to reach another chargingstation or another docking terminal at the charging station; direct theUAV to another charging station or another docking terminal at thecharging station in response to determining that the available powerlevel of the battery is sufficient to reach another charging station oranother docking terminal at the charging station; and land the UAV at alocation removed from the docking terminal to wait for the dockingterminal to become available to the UAV for charging in response todetermining that the available power level of the battery isinsufficient to reach another charging station or another dockingterminal at the charging station.
 18. The UAV of claim 10, wherein theprocessor is further configured to: determine, in response to receivingthe message from the charging station with the instruction to undock,whether the UAV is able to undock from the docking terminal at thecharging station; and stay docked at the docking terminal in response todetermining that the UAV is not able to undock from the dockingterminal.
 19. An unmanned aerial vehicle (UAV), comprising: means forcharging an onboard battery of the UAV while docked at a dockingterminal of a charging station; means for receiving a message from thecharging station with an instruction to undock from the dockingterminal; and means for undocking from the docking terminal beforecharging of the onboard battery is complete in response to receiving themessage from the charging station with the instruction to undock.
 20. Aprocessor configured for use in an unmanned aerial vehicle (UAV) andconfigured to: charge an onboard battery of the UAV while docked at adocking terminal of a charging station; receive a message from thecharging station with an instruction to undock from the dockingterminal; and undock from the docking terminal before charging of theonboard battery is complete in response to receiving the message fromthe charging station with the instruction to undock.
 21. The processorof claim 20, wherein the processor is further configured to: determine,in response to receiving the message from the charging station with theinstruction to undock, whether an available power level of the onboardbattery is sufficient to reach another charging station or anotherdocking terminal at the charging station; and land the UAV at a locationremoved from the docking terminal to wait for the docking terminal tobecome available to the UAV for charging in response to determining thatthe available power level of the onboard battery is insufficient toreach another charging station or another docking terminal at thecharging station.
 22. The processor of claim 21, wherein the processoris configured with processor-executable instructions such that landingthe UAV at the location removed from the docking terminal includeslanding the UAV on the charging station in a waiting zone separated fromthe docking terminal.
 23. The processor of claim 20, wherein theprocessor is configured with processor-executable instructions such thatthe received message from the charging station with the instruction toundock includes authorization to remain at the charging station but notin the docking terminal.
 24. The processor of claim 23, wherein theprocessor is further configured to: direct the UAV, in response toreceiving the message from the charging station with the instruction toundock, to move to a location at the charging station that is not in thedocking terminal.
 25. The processor of claim 21, wherein the processoris further configured to: determine whether the docking terminal hasbecome available; and redock at the docking terminal in response todetermining that the docking terminal has become available.
 26. Theprocessor of claim 20, wherein the processor is further configured to:determine, in response to receiving the message from the chargingstation with the instruction to undock, whether an available power levelof the onboard battery is sufficient to reach a destination of the UAV;and direct the UAV to head to the destination after undocking from thecharging station in response to determining that the available powerlevel of the onboard battery is sufficient to reach the destination ofthe UAV.
 27. The processor of claim 26, wherein the processor is furtherconfigured to: determine, in response to determining that the availablepower level of the onboard battery is not sufficient to reach thedestination of the UAV, whether an available power level of the onboardbattery is sufficient to reach another charging station or anotherdocking terminal at the charging station; direct the UAV to anothercharging station or another docking terminal at the charging station inresponse to determining that the available power level of the onboardbattery is sufficient to reach another charging station or anotherdocking terminal at the charging station; and land the UAV at a locationremoved from the docking terminal to wait for the docking terminal tobecome available to the UAV for charging in response to determining thatthe available power level of the onboard battery is insufficient toreach another charging station or another docking terminal at thecharging station.
 28. The processor of claim 20, wherein the processoris further configured to: determine, in response to receiving themessage from the charging station with the instruction to undock,whether the UAV is able to undock from the docking terminal at thecharging station; and stay docked at the docking terminal in response todetermining that the UAV is not able to undock from the dockingterminal.